Added flag to stop main Makefile in case of the error
Added flag to stop main Makefile in case of the error

JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples,JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples,JPETTomography/j-pet-framework-examples,JPETTomography/j-pet-framework-examples,wkrzemien/j-pet-framework-examples